import math
point=list(map(float,input().split()))
print(math.sqrt(pow(point[2]-point[0],2)+pow(point[3]-point[1],2))) import math math point=list(map(float,input().split())) point list(map(float,input().split())) list map(float,input().split()) map float input().split() ().split () input split print(math.sqrt(pow(point[2]-point[0],2)+pow(point[3]-point[1],2))) print math.sqrt(pow(point[2]-point[0],2)+pow(point[3]-point[1],2)) math.sqrt math sqrt pow(point[2]-point[0],2)+pow(point[3]-point[1],2) pow(point[2]-point[0],2) pow point[2]-point[0] point[2] point 2 point[0] point 0 2 pow(point[3]-point[1],2) pow point[3]-point[1] point[3] point 3 point[1] point 1 2 point=list(map(float,input().split())) list(map(float,input().split())) point
import math
point=list(map(float,input().split()))
print(math.sqrt(pow(point[2]-point[0],2)+pow(point[3]-point[1],2)))